Residential Building Codes Illustrated: A Guide to Understanding the 2009 International Residential Code

By Steven R. Winkel, David S. Collins and Steven P. Juroszek

An easy-to-use illustrated guide to building codes for residential structures

As the construction industry moves to a single set of international building codes, architects and construction professionals need an interpretive guide to understand how the building code affects the early design of specific projects. This newest addition to Wiley’s series of focused guides familiarizes code users with the 2009 International  Residential Code® (IRC) as it applies to residential buildings. The book provides architects, engineers, and other related building professionals with an understanding of how the International Residential Code was developed, and how it is likely to be interpreted when applied to the design and construction of residential buildings.
•    User-friendly visual format that makes finding the information you need quick and easy
•    The book’s organization follows the 2009 International Residential Code itself
•    Nearly 900 illustrations, by architectural illustrator Steven Juroszek in the style of noted illustrator and author Frank Ching, visualize and explain the codes
•    Text written by experienced experts who have been instrumental in gaining acceptance for the new unified building code

This book is an essential companion to the IRC for both emerging practitioners and experienced practitioners needing to understand the new IRC.

• Language: English
• Publisher: Wiley
• Release date: Jul 26, 2010
• ISBN: 9780470916490

Book preview

Preface

The primary purpose of this book is to familiarize code users with the use of the 2009 International Residential Code® (IRC) with a focus on the code provisions related to building construction. It is intended as an instructional text on how the code was developed and how it is organized, as well as a reference document on how to use the code for the design of one- and two-family dwellings. It is intended to be a companion to the IRC, not a substitute for it. This book must be read in concert with the IRC.

This book is designed to give an understanding of how the International Residential Code was developed, and how it is likely to be interpreted when applied to the design and construction of single family houses, two-family houses and townhouses no more than three stories high and with separate entries for each townhouse. The intent of this book is to give a fundamental understanding of the relationship of codes to practice for design professionals, especially those licensed or desiring to become licensed as architects, engineers or other related design professionals. Code knowledge is among the fundamental reasons for licensing design professionals, for the protection of public health, safety and welfare. It is our goal to make the acquisition and use of code knowledge easier and clearer for code users.

Many designers feel intimidated by building codes. Codes can seem daunting and complex at first glance. It is important to know that they are a product of years of accretion and evolution. Sections start simply and become more complex as they are modified, and new material is added to address additional concerns or to address interpretation issues from previous code editions. The complexity of a building code often comes from this layering of new information upon old without regard to overall continuity. Building codes are living documents, constantly under review and modification. It is vital to an understanding of codes to keep in mind that they are a human institution, written by ordinary people with specific issues in mind or specific agendas they wish to advance.

BUILDING CODE

Webster’s Third New International Dictionary defines a building code as: A set of rules of procedure and standards of materials designed to secure uniformity and protect the public interest in such matters as building construction and public health, established usually by a public agency and commonly having the force of law in a particular jurisdiction.

How This Book Is Organized

The first two chapters of this book give background and context regarding the development, organization and use of the IRC. Chapters 3 through 10 are organized and numbered the same as the corresponding subject-matter chapters in the IRC.

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Target Audiences

This book addresses code issues specific to the design and construction of dwellings. It accompanies and expands upon the basic principles addressed in the 2009 International Residential Code® (IRC).

For Emerging Professionals

Whether encountered during the design, production, management or construction administration phases for construction of one- and two-family dwellings and townhouses, codes and standards are an integral and inescapable part of the practice of architecture and engineering. New practitioners need to refine their skills and knowledge of codes to make their projects safe and buildable with few costly changes. The more practitioners know about the code the more it can become a tool for design rather than an impediment. The better the underlying criteria for code development and the reasons for code provisions are understood the easier it is to create code-compliant designs. Early understanding and incorporation of code-compliant design provisions in a project reduces the necessity for costly and time-consuming rework or awkward rationalizations to justify dubious code decisions late in project documentation, or even during construction. Code use and understanding should be part of accepted knowledge for professionals, so that it becomes a part of the vocabulary of design.

For Experienced Practitioners

The greatest value of this book is that it is based upon the broadly adopted International Residential Code. This is a code that is similar but by no means identical to the old Council of American Building Officials (CABO) One- and Two-Family Dwelling Code that many experienced practitioners have used in the past. New state and federal standards have been developed using the IRC and the new requirements, while similar, are by no means identical to those in prior codes. This book will guide experienced practitioners out of the old grooves of code use they may have fallen into with the old codes. The code-analysis methods and outcomes will vary between the old codes and the new IRC. While there are seemingly familiar aspects from each code interspersed throughout the new code, the actual allowable criteria and how they are determined are often quite different. It is likely that the illustrations and the underlying reasons for the development of each code section will look familiar to experienced practitioners. The experienced practitioner must not rely on memory or old habits of picking construction types or assemblies based on prior practice. Each dwelling must be looked at anew until the similarities and sometimes-critical differences between the new code and old habits are understood and acknowledged.

It is also worth remembering that building officials and plan checkers are now becoming more familiar with these codes as well. We are still in a period of transition during which dialogue between designers and plan reviewers will be essential. The precedents that people on each side of the plan-review counter in the building department are most familiar with may no longer apply. Designers and building officials must arrive at new consensus interpretations together as they use the new codes for specific projects.

How to Use This Book

This book focuses on the use and interpretation of the provisions of the 2009 International Residential Code® (IRC). There are references to basic structural requirements, but this book does not attempt to go into the derivation of the structural requirements in depth. That is a subject for another volume. This book does discuss and illustrate the prescriptive structural requirements contained in the IRC. This book covers the first 10 chapters of the IRC. These chapters are the core of the provisions related to building planning and building structure. These chapters cover requirements for the major components of the building envelope: foundations, floors, walls and roofs. This volume does not address provisions for energy efficiency or requirements for mechanical, electrical or plumbing work.

The organization of this book presumes that the reader has a copy of the latest version of the IRC itself as a companion document to this book. The book is intended to expand upon, interpret and illustrate various provisions of the code. The IRC has been adopted in many jurisdictions. It is now being extensively applied, and while there is not yet a large body of precedent in application and interpretation, code users do have a history of prior use to draw upon. It is our hope that the analysis and illustrations in the book will aid the designer and the Authorities Having Jurisdiction (AHJ) in clarifying their own interpretations of the application of code sections to projects.

The book is not intended to take the place of the 2009 International Residential Code® in any way. The many detailed tables and criteria contained in the IRC are partially restated in the book for illustrative purposes only. For example, we show how various tables are meant to be used and how we presume certain parts will be interpreted. When performing a code analysis for a specific project, we anticipate the reader will use our book to understand the intent of the applicable code section and then use the code itself to find the detailed criteria to apply. One can, however, start with either the IRC or this book in researching a specific topic:

Beginning with the 2009 International Residential Code®

• Search Contents or Index.

• Read relevant section(s).

• For further explanation and/or clarification, refer to this book.

Beginning with Residential Building Codes Illustrated

• Search Code Index for section number or Subject Index for topic.

• Refer back to specific text of 2009 International Residential Code®.

The text is based upon the language of the code and interprets it to enhance the understanding of the user. The interpretations are those of the authors and may not correspond to those rendered by the AHJ. We would encourage the users of the book to confer with the AHJ early in the design process, using the illustrations from this book to validate interpretations. Reconciling text with construction drawings often benefits from additional illustrations. We trust that this will be the case with the explanations and graphics in this book.

Metric Equivalencies

The 2009 International Residential Code® uses the following SI units.

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Building Codes

The existence of building regulations goes back almost 4,000 years. The Babylonian Code of Hammurabi decreed the death penalty for a builder if a house he constructed collapsed and killed the owner. If the collapse killed the owner’s son, then the son of the builder would be put to death; if goods were damaged then the contractor must repay the owner, and so on. This precedent is worth keeping in mind as you contemplate the potential legal ramifications of your actions in designing and constructing a building in accordance with the code. The protection of the health, safety and welfare of the public is the basis for professional licensure and the reason that building regulations exist.

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"If a builder build a house for some one, and does not construct it properly, and the house which he built fall in and kill its owner, then that builder shall be put to death.

If it kill the son of the owner, the son of that builder shall be put to death.

If it kill a slave of the owner, then he shall pay slave for slave to the owner of the house.

If it ruin goods, he shall make compensation for all that has been ruined, and inasmuch as he did not construct properly this house which he built and it fell, he shall re-erect the house from his own means.

If a builder build a house for some one, even though he has not yet completed it; if then the walls seem toppling, the builder must make the walls solid from his own means."

Laws 229-233

Hammurabi’s Code of Laws

(ca. 1780 BC)

From a stone slab discovered in 1901 and preserved in the Louvre, Paris.

Various civilizations over the centuries have developed building codes. The origins of the codes we use today lie in the great fires that swept cities regularly in the 1800s. Concerns about fire regulations in urban areas can even be seen dating as far back as the Great Fire of London in 1666. Chicago developed a building code in 1875 to placate the National Board of Fire Underwriters who threatened to cut off insurance for businesses after the fire of 1871. It is essential to keep the fire-based origins of the codes in mind when trying to understand the reasoning behind many code requirements.

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The various and often conflicting city codes were refined over the years and began to be brought together by regional nongovernmental organizations to develop so-called model codes. These model codes were developed and written by members of the code organizations. The codes were then published by those code organizations. Model codes are developed by private code groups for subsequent adoption by local and state government agencies as legally enforceable regulations. The first major model-code group was the Building Officials and Code Administrators (BOCA), founded in 1915. They published the BOCA National Building Code. Next was the International Conference of Building Officials (ICBO), formed in 1922. The first edition of their Uniform Building Code was published in 1927. The Southern Building Code Congress, founded in 1940, published the Standard (Southern) Building Code.

These three model-code groups published the three different building codes previously in widespread use in the United States. These codes were developed by regional organizations of building officials, building materials experts, design professionals and life safety experts to provide communities and governments with standard construction criteria for uniform application and enforcement. The ICBO Uniform Building Code was used primarily west of the Mississippi River and was the most widely applied of the model codes. The BOCA National Building Code was used primarily in the north-central and northeastern states. The SBCCI Standard Building Code was used primarily in the Southeast. The model-code groups have merged together to form the International Code Council and have ceased maintaining and publishing their own codes. Also included in this merger was the incorporation of the Council of American Building Officials (CABO) into the International Code Council. CABO published the One- and Two- Family Dwelling Code. This code, which was limited in coverage to the types of occupancies noted in its title, was the closest thing to a national model building code in the decades preceding the development of the International Building Code.

The International Building Code

Over the past few years a real revolution has taken place in the development of model codes. There was recognition in the early 1990s that the nation would be best served by comprehensive, coordinated national model building codes developed through a general consensus of code writers. There was also recognition that it would take time to reconcile the differences between the existing codes. To begin the reconciliation process, the three model codes were reformatted into a common format. The International Code Council, made up of representatives from the three model-code groups, was formed in 1994 to develop a single model code using the information contained in the three current model codes. While detailed requirements still varied from code to code, the organization of each code became essentially the same after the mid-1990s. This allowed direct comparison of requirements in each code for similar design situations. Numerous drafts of the new International Building Code were reviewed by the model-code agencies along with code users. From that multiyear review grew the International Building Code (IBC), first published in 2000. There is now a single national model building code, maintained by a group composed of representatives of the three prior model-code agencies, the International Code Council, headquartered in Washington, D.C. This group was formed from a merger of the three model-code groups and CABO into a single agency to update and maintain the I Code family, which includes the International Building Code and the International Residential Code.

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The International Residential Code

In addition to the International Building Code (IBC) there is the International Residential Code (IRC). This stand-alone code is meant to regulate construction of detached one- and two-family dwellings and townhouses that are not more than three stories in height with a separate means of egress. This code is designed to supplant residential requirements contained in the IBC in jurisdictions where the IRC is adopted.

The IRC is derived from a predecessor residential building code published by the Council of American Building Officials (CABO), the One- and Two-Family Dwelling Code. In 1996 CABO and the predecessor code organizations that ultimately became the International Code Council agreed to begin development of an updated stand-alone national model residential building code. This resulted in the first publication of the International Residential Code in 2000. This code includes provisions that replace the requirements of the International Building Code with requirements specific to buildings within the scope of the IRC. The IRC includes provisions for code requirements for all the systems typically contained in the one- and two-family buildings and townhouses regulated by the IRC. Among these external codes are the electrical sections of the IRC, which are taken from NFPA 70: National Electrical Code. The electrical chapters are produced under the auspices of the National Fire Protection Association (NFPA), which produces and copyrights the National Electrical Code. The IRC also contains materials regarding fuel gas provisions included through an agreement with the American Gas Association (AGA). [Note this book focuses on the first 10 chapters of the IRC, the requirements related to building design and construction, and does not address IRC requirements for such things as electrical or plumbing work.]

Note also that many local jurisdictions make other modifications to the codes in use in their communities. For example, many jurisdictions make amendments to require fire sprinkler systems, even in single-family residences, where they may be optional, or not even required, in the model codes. In such cases mandatory sprinkler requirements may change the design options offered in the model code for inclusion of sprinklers where not otherwise required by the code. It is imperative that the designer determines what local adoptions and amendments have been made in order to be certain which codes apply to a specific project.

There are also specific federal requirements that may need to be considered in design and construction in addition to the locally adopted version of the model codes. Among these are the Americans with Disabilities Act of 1990 and the Federal Fair Housing Act of 1988. While knowledge of these regulations will promote universal design for access to housing for persons with disabilities, note that these regulations typically do not apply to the types of buildings regulated by the International Residential Code. Accordingly they will not be discussed in any detail in this book.

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Code Interactions

The Authorities Having Jurisdiction (AHJ)—a catch-all phrase